The exchange of Ca2+ ions in hydroxyapatite (HAp) with Zn2+ into Zn-HAp is interest for applications ranging from bone tissue engineering to the use as a precursor subsequent ion-exchange reactions. Previous studies, using direct synthesis, showed that ~ 20 mol% can be incorporated HAp, before byproducts are observed. However, this realized at cost loss crystallinity and control over crystal si...

In this paper, CdSe nanocrystal dissolution in an aqueous solution was studied. It was found that light is a key factor affecting the dissolution of nanocrystals. In the presence of light, the electrons generated from CdSe nanocrystals reduce water to hydrogen and hydroxide ions (OH-) while photo-generated holes oxidize CdSe to Cd2+ and elemental Se. The dissolution was accelerated in an acidic...

Abstract. An accurate prediction of the ice crystal number concentration in clouds is important to determine radiation budget, lifetime, and precipitation formation clouds. Secondary-ice production thought be responsible for observed discrepancies between ice-nucleating particle The Hallett–Mossop process active ?3 ?8 ?C has been implemented into several models, while all other secondary-ice pr...

Decadal and centennial mean state changes in South American summer monsoon (SASM) precipitation during the last 2,300 years are detailed using an annually resolved authigenic calcite record of precipitation δ(18)O from a varved lake in the Central Peruvian Andes. This unique sediment record shows that δ(18)O peaked during the Medieval Climate Anomaly (MCA) from A.D. 900 to 1100, providing evide...

Dental fluorosis was first described in 1916 by GV Black and FS McKay.4 The process occurs beginning with fluorides being absorbed via the stomach and small intestine, and then largely excreted via the kidneys. Any ingested fluoride is stored in the mineralized tissues – bone, teeth – and at a level that increases with age.5 Odontogenesis is a sequential process moderated by epithelial-mesenchy...

The molecular structure of the units that get incorporated into the nuclei of the crystalline phase and sustain their growth is a fundamental issue in the pathway from a supersaturated solution to the formation of crystals. Using a fluorescent dye we have recorded the variation of the pH value in time along a gel where CaCl2 and NaHCO3 counter-diffuse to crystallize CaCO3. The same pH-space-tim...

Snowpack evolution and glacier ice surface temperatures were studied on the Indren glacier (Northwestern Alps, Italy) under different meteorological conditions: in winter 2002–2003, rich in snow from the beginning of the season, and in winter 2005– 2006, poor in snow until February. Periodical snow profiles were made to measure the physical properties of snow, while data loggers measured the sn...

Autoionization of water which gives rise to its pH is one of the key properties of aqueous systems. Surfaces of water and aqueous electrolyte solutions are traditionally viewed as devoid of inorganic ions; however, recent molecular simulations and spectroscopic experiments show the presence of certain ions including hydronium in the topmost layer. This raises the question of what is the pH (def...

The potential applications of ice-templating porous materials are constantly expanding, especially as scaffolds for tissue engineering. Ice-templating, a process utilizing ice nucleation and growth within an aqueous solution, consists of a cooling stage (before ice nucleation) and a freezing stage (during ice formation). While heat release during cooling can change scaffold isotropy, the freezi...